Boys town is not the movie to see for the inside view on child- welfare problems. Ladybird, Ladybird is. This English drama about a worst-case child-custody scenario may show those who make social policy how hard it is to legislate love, lust, neglect, despair and other real-family values. Ken Loach's film, written by Rona Munro and based on a true story, horrifies and edifies in equal measure.

Maggie Conlon (Crissy Rock) is a working-class mess. She has had four children by four men. She does care for...